"He's refusing to be accountable," Mulcair said today in the Commons' daily question period.

"He's the one who put this self-regulating system in place. He is responsible. Why is this minister of agriculture still in his position? He must resign."

Ritz was not offering his resignation and defended Canada's food inspection system.

"We take this very seriously," Ritz told the MPs Thursday in response.

"We're working to ensure the CFIA (Canada Food Inspection Agency) has the regulations that they require and the monetary capacity to get the job done."

Ritz was peppered with questions about the E. coli outbreak throughout question period.

Interim Liberal Leader Bob Rae accused the government of moving too slowly to curb the crisis. Rae said authorities in the U.S. stopped imports from the XL Food plants on Sept. 13 while Canada did not shut down the plant until Sept. 27.

"Americans were protected on Sept. 13 because no product was allowed to be exported to the United States," Rae said.

"All Canadian consumers were not protected until Sept. 27, two weeks later. Why were Americans better protected than Canadians?"

Ritz accused the opposition of "cherry-picking" the timeline of events in the E. coli outbreak.